The present invention relates to a large, heavy-duty turntable assembly of the type used for transferring or indexing heavy workpieces or parts such as motor vehicle parts. Such turntable assemblies are generally disclosed, for example, in U.S. Pat. Nos. 4,285,233, 4,795,021 and 6,435,397. In this type of turntable assembly which may be used to transfer motor vehicle frames or body parts to robotic welders, it is highly desirable for the assembly to have a low profile above the floor without requiring a pit within the floor to receive an indexing drive mechanism so that the assembly may be located anywhere in a manufacturing plant. A low profile turntable is also desirable in order to avoid using man stands or platforms for the operators to work and/or to avoid the need to elevate the heavy parts when loading the parts onto an elevated turntable and the need to lower the parts from the turntable.
A low profile turntable also provides for operator ergonomics and enables the turntable to be conveniently used and serviced. This is especially desirable when the parts being loaded, transferred and unloaded have substantial weight such as several thousand pounds, and the tools or fixtures which are mounted on the turntable for supporting the parts also have substantial weight, for example, five thousand to six thousand pounds. It is further desirable for a loaded turntable to rotate or index or oscillate quickly and precisely so that there is minimal down time of the equipment adjacent the turntable, such as robotic welders, which perform operations on the parts after they are indexed or transferred.